Cryptography: The Key to Digital Security, How It Works, and Why It Matters

by Keith Martin

Overview

A nuts-and-bolts explanation of cryptography from a leading expert in information security.

Despite its reputation as a language only of spies and hackers, cryptography plays a critical role in our everyday lives. Though often invisible, it underpins the security of our mobile phone calls, credit card payments, web searches, internet messaging, and cryptocurrencies—in short, everything we do online. Increasingly, it also runs in the background of our smart refrigerators, thermostats, electronic car keys, and even the cars themselves. As our daily devices get smarter, cyberspace—home to all the networks that connect them—grows.

Broadly defined as a set of tools for establishing security in this expanding cyberspace, cryptography enables us to protect and share our information. Understanding the basics of cryptography is the key to recognizing the significance of the security technologies we encounter every day, which will then help us respond to them.

What are the implications of connecting to an unprotected Wi-Fi network? Is it really so important to have different passwords for different accounts? Is it safe to submit sensitive personal information to a given app, or to convert money to bitcoin? In clear, concise writing, information security expert Keith Martin answers all these questions and more, revealing the many crucial ways we all depend on cryptographic technology. He demystifies its controversial applications and the nuances behind alarming headlines about data breaches at banks, credit bureaus, and online retailers. We learn, for example, how cryptography can hamper criminal investigations and obstruct national security efforts, and how increasingly frequent ransomware attacks put personal information at risk. Yet we also learn why responding to these threats by restricting the use of cryptography can itself be problematic.

Essential reading for anyone with a password, Cryptography offers a profound perspective on personal security, online and off.

Product Details

ISBN-13:	9781324004295
Publisher:	Norton, W. W. & Company, Inc.
Publication date:	05/19/2020
Pages:	320
Product dimensions:	6.40(w) x 9.30(h) x 1.30(d)

About the Author

Keith Martin is a professor of information security at Royal Holloway, University of London, and has worked in cryptographic research for thirty years. He lives in Surrey, United Kingdom.

Table of Contents

Introduction 1

1 Security in Cyberspace 11

2 Keys and Algorithms 26

3 Keeping Secrets 46

4 Sharing Secrets with Strangers 72

5 Digital Canaries 93

6 Who's Out There? 125

7 Breaking Cryptosystems 157

8 The Cryptography Dilemma 197

9 Our Cryptographic Future 228

Acknowledgments 251

Notes 253

Index 299

Editorial Reviews

03/02/2020

Martin (Everyday Cryptography), an information security scholar, provides a useful introduction to cryptography, successfully showing the field isn’t one “only computer whiz kids have any hope of understanding.” Underlining cryptography’s importance, he observes that digital encryption “underpins everyone’s security in cyberspace,” from online shopping to keyless car entry. Starting at the most basic level of computer science, Martin explains how binary code works, before moving to more advanced topics such as symmetric encryption and hash functions. He shows a knack for communicating demanding ideas, breaking up the text into short chunks, echoing the structure of block cipher and with the same result of facilitating quick deciphering of sometime complex information. He also deploys physical metaphors for the abstract cryptographic tools he covers, describing asymmetric encryption, for instance, as a series of padlocks attached to a briefcase, and the challenge-response principle as a blind boomerang hunter. For historical context, Martin connects today’s encryption techniques to codes used by the likes of Julius Caesar and Mary, Queen of Scots. At the close, he discusses the difficult balancing act between security and personal privacy, and likely future developments in the cryptographic field. This timely book will leave digital neophytes significantly better informed about a vital area in computer science. (May)

Publishers Weekly

"Encryption is both one of the most fiercely contested and one of the least understood tech-policy issues of our time. Keith Martin has written an indispensable guide to the ongoing crypto wars—balanced, gripping, and in plain English."

Thomas Rid

"Keith Martin has a knack for explaining one of today’s toughest inter-disciplinary problems in an accessible and accurate way. There’s no math required, just a willingness to engage your brain. You will finish this book both entertained and better informed."

Kenny Paterson

"In his typical low-key style, Keith Martin explains how digital security is necessarily based on cryptosystems, secret keys, and public keys. A must-read for anyone who wants to participate competently in discussions on the role of cryptography in our society"

Vincent Rijmen

2020-02-09
If Napoleon had had better passwords, you might be reading this in French today.

Computers may be new, historically speaking, but cryptography is as old as writing. Martin, a British professor of information security who wrote one of the standard texts on the topic, Everyday Cryptography, delivers numerous examples of failed codes from the past, including one that cost Julius Caesar dearly and another that essentially sent Napoleon packing to Saint Helena. On the matter of that Napoleonic code, Martin writes that it was “designed to counter frequency analysis” by blending plain text letters into “ciphertext” along with “masking common letter combinations using dummy characters.” As with much that is technological, operator error ruined a good thing: The soldiers entrusted with the job encrypted only parts of the French military’s communications, and the British soon decoded “La Grande Chiffre de Paris.” Every code will eventually be broken, and passwords like “password” and “god123” are going to be cracked in a second. In this survey, Martin gives readers the essentials of cryptography without much by way of the underlying numbers even though cryptography is, strictly speaking, a branch of mathematics. Even though “you can breeze through life using cryptography without even being aware of it,” courtesy of the algorithms hidden away on your bank site and in your smartphone, it’s better to know a little about the devices and formulas by which messages go from one place to another without being intercepted and decoded. The author’s text, while readable and indeed even elementary at times (“ASCII…defines the rules for switching between keyboard characters and bits”), requires a high tolerance for nerdspeak and the ability to deal with terms such as “transport layer security” and “challenge-response” without immediately dozing off. Regardless, it’s highly informative and offers a good argument for hardening one’s digital security.

Tech-savvy readers will come away with a greater appreciation for the science involved in keeping secrets from prying eyes.

Kirkus Reviews

"In his searching and authoritative book, Keith Martin explains how…cryptography governs a huge portion of everyday life, and this book is the perfect introduction."

Open Letters Review - Steve Donoghue